By Sean Cumming, Professor in Paediatric Exercise Science at the University of Bath

Understanding the growth spurt is key to developing elite talent, like England’s greatest goalscorer plus a host of Premier League stars – and can have a huge public health legacy.

Should Harry Kane inspire England to European Championship success this summer and pick up the first major trophy of his career aged 30, he may reflect back to a pivotal moment in his teenage years. Kane was in Arsenal’s Academy as a youngster but was considered too small and did not make the cut. He was then picked up by London rivals Tottenham and Richard Allen, the former Head of Academy Recruitment at Spurs, who also had initial doubts as to whether Kane possessed the physical attributes necessary to succeed as a professional footballer. Their decision to retain the player, who would go on to become the greatest goalscorer in the club’s history, rested upon their recognition of two factors: one, he was a ‘late birthday’ (28th July) – meaning that he was one of the youngest in his age group. Secondly, Spurs identified that he was a later maturer, and that what he lacked in physicality he made up for in his unwavering technical prowess and psychological fortitude.

In coming to their decision, they looked at Kane’s dad, who was over 6ft, and thought that if he turned out anywhere close to that height, then physically he’d be capable enough to succeed in football. Then, the sports scientist who worked with him, Anton McElhone – who later moved to Celtic and is now with Queen's Park – noted that for his age group, Kane was average for fitness, strength, and power. But that for his developmental status, he was well above average. So, they concluded, that as Harry had much more room to grow and develop physically than the other boys, when he eventually caught up with and/or surpassed them he would be one of the best by a long shot.

The necessity to protect late developers, so as not to lose out on talents like Kane, became a big push for the Premier League and many of their leading clubs to invest in the area of growth and maturation. In 2015, my colleagues and I at the University of Bath worked with the Premier League to establish academy-wide growth maturity screening programmes, which they integrated into their player monitoring systems as part of the Elite Player Performance Plans (EPPP). So, that meant that every academy in the Premier League was required to measure and track their players’ growth and maturation every three or four months. To educate academy staff and practitioners on how to measure growth and maturation – and the importance of these processes for player development – the league also held a series of educational workshops on the topic. Armed with a greater knowledge and understanding of growth and maturation, and with more capacity to identify those early and late developers, the Premier League academies quickly established themselves as leaders in the practice of managing growth and maturation in young athletes.

Another of the big concerns for the Premier League academies was that young players were more susceptible to sustaining lots of growth-related injuries during the adolescent growth spurt. The growth spurt occurs first in the skeleton and, six-to-nine months later, the soft tissues (muscles and tendons) catch up. So, at the height of the growth spurt, you get a lot of additional stress and tension on the points of the musculoskeletal system where the ligaments and the tendons are attached to the bone, and also at the growth plates which are more fragile due to rapid growth. If you're really ramping up training at the point at which kids are developing rapidly, then it can lead to growth-related conditions like Sever’s, Osgood-Schlatter, Pars, sclerosis, and stress fractures.

With the data that the league collected and fed back to clubs, academy staff were able to better predict and identify the onset of the growth spurt and effectively reduce the risk of injury by adapting training intensity and content. The clubs brought in their own changes, like the introduction of bio-banding – the process of grouping athletes based on attributes associated with growth and maturation, rather than chronological age. In fact, you won't find a better, more well-informed league than the Premier League when it comes to these issues and practices.

An example of good early practice in the management of growth and maturation in academy players was under Sir Alex Ferguson at Manchester United. He had spotted that a lot of the academy players were picking up injuries during the growth spurt. And so, they hired Dr Amanda Johnson, who served as the senior physiotherapist at the academy for 10 years. She started taking regular assessments of growth and maturation and found that within the age groups, there could be a biological difference of about five to six years between the early and late maturing boys. So, she had nine-year-olds who were biologically 12 and other nine-year-olds who were biologically six or seven. And, of course, they were playing and training in the same age group.

They realised that some of the later developing players, like Danny Welbeck and Jesse Lingard for example, were exceptionally talented yet struggled to compete physically with many of the earlier developing players within their age groups. The biggest risk in talent identification – which Ferguson highlighted in his book on leadership – was investing in a big, early-developing boy over a late-developing boy who is technically and tactically much better. So, players such as Welbeck and Lingard ended up playing down one or two age groups for periods of time because developmentally that was the most appropriate challenge for them. They would have had data on Paul Scholes too, who is another great example of a late developer who was well managed and thrived in United’s Academy. Being so far ahead of the game on this issue is one of a number of reasons that United were, and continue to be, so successful in transitioning a lot of the boys from the academies to the first team.

Southampton FC are another interesting case study. They had previously released Danny Ings and Tyrone Mings in their academy, and both were let go for being considered too small. Then came Alex Oxlade-Chamberlain. Alex was a very talented boy within the academy, but he was also a late developer. From their assessments, they knew that physically he wasn't ready to move up an age group. So, they sat down with his dad, Mark Chamberlain, a former player, and his mother. They suggested that, for Alex, remaining within his previous age group would be the right decision for him at that point in time because he was a late developer. If they put him up into the next age group, he would struggle to compete or get enough of the ball. Physically, he would be dominated. So, for him to develop at that stage, this is where he needed to be. Alex played down an age group for a year and then went through his growth spurt. By 16, he had caught up with his peers, was pretty much a fully grown man and started to feature for the first team.

Another classic example was Gareth Bale. Gareth was in the Southampton Academy and started to go through his growth spurt at 15. Prior to that point, he’d been a standout player. All of a sudden, he lost his coordination, the quality of his performances dipped and there were lots of questions asked about him. “Is he somebody we want to invest in and give a scholarship to?” He survived a scholarship decision largely down to the insight of an academy staff member who flagged up that he was going through his growth spurt and there might be a temporary disruption as he got used to the changes. They took Bale aside and adapted his training to work more on his core strength, balance and coordination, retraining those functional and sports-specific skills – and within a matter of months he was back playing at his high level. Had they not identified that he was going through his growth spurt, they could have lost their biggest talent.

At the same time, it's as much about challenging the early developer. Arsenal’s Bukayo Saka was a classic early developer, yet possessed many of the technical, tactical and psychological attributes that the late developers need to have to survive in the system. Not all early developing players will, however, be as fortunate and this is why it is important to make sure that those early developing kids are also challenged in the right ways and given optimal opportunity to develop these attributes as well.

A lot of our work with the Premier League crosses over with Podium Analytics, in terms of affording equal opportunities, challenging early and late developing children and reducing the number of growth-related injuries in schoolchildren. One of the most obvious areas is the growth spurt and growth-related injuries. In partnership with Podium, we have started to create an online Continuing Professional Development (CPD) education programme for PE teachers and sports coaches working in schools. The majority of PE teachers and school sports coaches do not receive formal education in terms of how children grow and develop, so there is a clear appetite to learn more about the subject matter. They'll now be aware of the early, on-time and late developers. They'll recognise some of the risks associated with injury and they'll have more competence to understand and adapt training programmes or PE lessons as appropriate.

For all the projects that Podium delivers – whether it’s looking at concussion or RED-S (Relative Energy Deficiency in Sport) – in order to understand injury or wellness in young people, you need to first understand how they grow and develop. So, I think this will be an important central programme in terms of upskilling PE teachers and improving knowledge and practice within the school system to better challenge and protect early, on-time and late developers.

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You can hear more from Sean Cumming about the growth spurt on the SportSmart Hub. Visit sportsmart.org/hub